How To Fix VW Golf Heater Problems

How To Fix VW Golf Heater Problems

When the temperature falls, you’ll naturally reach for the heater controls in your car. But what if they don’t work or you end up with even more cold air blasting through your cabin? There’s no excuse for having a chilly car when it's freezing outside, so here are some tips on how to sort out some of the most common VW Golf heater problems…

How does the VW Golf heater work?

The best place to start on this topic is with an overview of how everything works. There are a few components that could cause you drama. The first is the heater matrix and the heater control valve, the second the heater blower motor, and lastly the fan control switch, to operate the blower. If all of these are working correctly you should stay nice and warm. If one or more are faulty, you could end up cold, very cold, or with wet feet! 

The fan control switch is electrically operated, however, the heater control valve and vents are typically adjusted by cables attached to the heater control panel on older vehicles. 

How does the heater blower work?

The heater blower is a variable speed fan mounted close to the heater matrix. It is operated by the heater switch and blows air through the heater matrix, making the air warm, before circulating it out into the cabin. 

You'll find it fixed under the scuttle panel on a Mk1 Golf, but water may have run in and started to rust the bearings causing the fan motor to seize. This problem will present itself when you try to switch it on. Whilst nothing will happen, the relevant fuse will probably blow! 

If the old blower needs to come out it must be removed from the inside, where it lives in the centre housing beneath the dashboard – sadly it is slightly too big to be removed out the top and through a non-smoothed engine bay as the firewall gets in the way.

If you have a Mk2 Golf, the heater blower is mounted under the dash, above the passenger footwell, and is a slightly easier job to remove. Whilst mounted inside the cabin, it is still prone to rainwater leaking through it, if the seal under the scuttle panel has been compromised. This will make itself known as a puddle in both the front and rear passenger side footwell.

But, before you pull the blower motor out, do double check you haven’t got a faulty heater switch on your hands. A new one can be bought for very little money, and it could save you a few hours messing around removing the dash. 

How does the heater matrix work?

The heater matrix is a small radiator that sits behind a bypass valve in your vehicle coolant system. When the bypass valve is closed, the coolant circulates the engine as normal, and your heater doesn't warm up. Once the bypass valve is opened, the hot coolant can move into the heater matrix warming it up.

This component is the source of most climate-related complications on the Golf and its booted brother the Jetta. When it fails your blower will be chucking out cold air not hot. This is could be caused by the matrix becoming blocked, leading to a split, which in turn soaks the passenger footwell with water; hopefully not your passenger’s feet with hot coolant.

Check under the bonnet where the inlet and outlet heater plumbing run into the bulkhead because it’s not unusual to find the heater matrix disconnected altogether, or the VW non-return valves removed or replaced by solid bits of pipe inserted to transport the water back and forth. Do note though, the replacement upgraded heater matrix we offer here already has this valve built-in, so will require the removal and bypass of the original valve in the engine bay. These are LHD and RHD specific, so make sure you source the correct one.

Even with the dashboard stripped down as photographed, you won't see the matrix as it is hidden right at the back of all the heater boxes. It is also worth replacing all the foam-covered flaps with new high-strength self-adhesive foam to ensure a decent seal and the correct channeling and distribution of the heat once the job is done. 

Whilst the matrix is typically at fault, don’t rule out airlocks causing an issue either. To get rid of these run the car with the expansion cap removed and the fan disconnected, let the water boil over, then turn the engine off and top up with more coolant.

What does the heater resistor do?

The heater blower resistor is responsible for regulating the speed of the heater fan when the switch is adjusted to each setting. 

If the heater on your classic Golf (or another water-cooled model) only works on its fastest setting the chances are the resistor on the fan pack behind the dash has failed, either due to corrosion or from overheating.

It can be dealt with in a couple of ways. Either you grab some tools and a soldering iron and replace the thermal overload resistor from the rear of the metal panel attached to the heater blower. Or, you buy a replacement part with the resistor already in place online here

Either way, it should fix the problem for you. 

Don't forget to check your coolant levels

So you’ve got rubbish heaters. Have you checked the coolant level in your expansion tank recently? It may sound simple, but if it’s dropped below the minimum mark, your heaters won’t be nearly as efficient. Topping up with the correct anti-freeze is a short-term solution; use what the manufacturer originally recommended and don’t mix two and five-year (Organic Acid Type) brews.

You will need to know why the level’s dropped in the first place though, and once you’ve ruled out obvious leaks the most likely culprit is the cylinder head gasket. If it’s failed, you’ll notice oil contamination in the water and water in the oil, in which case there will be a creamy white deposit on the underside of the oil filler cap. And you thought having cold feet was your only worry!

Best of luck, and fingers crossed for a quick and easy fix. 

Ian/ Andy

4 months ago
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